I. Field of the Invention
This invention relates generally to ground anchors adapted for use in securing an above ground load to the ground, and more particularly to a low-cost highly effective ground anchor especially adapted for securing concrete erosion control mats in place in drainage ditches, creek bottoms and the like.
II. Discussion of the Prior Art
In the Crow et al. Patent there is described a mat comprising a plurality of concrete blocks which are arranged in a matrix and strung together by means of rods, chains or cables extending through the blocks. The mats are used for reducing erosion caused by running water streams, such as may be present in drainage ditches, culverts, irrigation channels, stream beds and the like. Because of the manner in which the concrete blocks are linked together, the mats are sufficiently flexible so as to generally conform to the ground on which they are laid. The mats are laid in manageable sized sections and must be held together and maintained in position when exposed to the substantial forces of rushing water.
In the past, it has been the practice to insert ground anchors at strategic points relative to the concrete mats and use cable or chain to join the ground anchors to the mats to prevent their migration. A particular ground anchor sold by International Erosion Control, Inc. is quite effective but has the drawback of being unduly expensive. That device is referred to as "duckbill anchor" and comprises a cast metal tubular body having one open end and one closed end. The open end has a beveled arcuate flair formed thereon. This anchor has an eyelet formed on a side wall thereof through which the cable or chain may loop. It is driven into the ground by inserting a pipe or solid rod into the open tubular end of the anchor and then, using a maul or other type of manual or automatic hammer, is driven deep into the ground. When the pipe or rod is removed from the insertion hole made and tension is applied to the cable linked to the anchor, the anchor tends to rotate because of the engagement of the flared duck-bill end with the ground, thus placing the anchor cross-wise relative to the hole through which it had been inserted into the ground. The more tension that is applied to the cable or chain, the more the anchor member rotates, thereby substantially increasing the force that would be required to pull it free of the earth.